The present invention relates to lithium-ion and/or lithium-ion polymer batteries, and more particularly to a lithium-ion or lithium-ion polymer battery having a protective insert to provide structural support and protection around battery leads and connections.
Broadly stated, a Li-ion and/or Li-ion polymer battery is generally comprised of a plurality of layered sections, namely, an anode section, a cathode section and a separator that is disposed between the anode section and the cathode section. Multi-layered cells are comprised of a plurality of anode and cathode sections.
Each anode section and each cathode section includes a layer of a conductive material that is disposed within or in contact with such sections. This layer is generally referred to as a xe2x80x9ccurrent collector.xe2x80x9d It is known to use metal screens, meshes or foils to form the aforementioned current collectors. Typically, copper mesh is used to form an anode current collector and an aluminum metal mesh is used to form a cathode current collector. Multi-layered cells typically include a plurality of anode current collectors and a plurality of cathode current collectors. Each current collector generally includes a short, outwardly extending tab that is ultimately connected to a battery lead. The battery leads are typically comprised of a flat, metallic strip, formed of copper, aluminum or nickel. It is therefore necessary to join all anode current collector tabs together and attach them to an anode battery lead. Likewise, all cathode current collector tabs must be joined together and attached to a cathode battery lead.
Typically, the cathode current collector tabs are joined together, and joined to a cathode battery lead, by ultrasonic welding. The welding procedure produces a xe2x80x9cweldmentxe2x80x9d or xe2x80x9cweld nuggetxe2x80x9d with the cathode battery lead extending therefrom. The weld nugget is disposed within the battery""s package with the cathode lead extending through the packaging to form an external cathode battery lead. In a similar manner, anode current collector tabs are attached to an anode lead that extends through the battery package to form an external anode battery lead.
Within the battery package, the weldments are disposed in an area conventionally referred to as xe2x80x9chead space.xe2x80x9d This area is essentially a void space within the battery provided to accommodate the weldments (nuggets). This void space within the battery package can cause the laminate forming the battery packaging to collapse or crumple in these areas during a battery de-gassing processes, wherein excess gas is removed from the battery package by drawing a vacuum therein. The negative, internal pressure within the battery package typically causes the packaging laminate to collapse wherever internal voids exist, thereby forming indentations or depressions in the outer surface of the packaging. Whenever the packaging laminate contacts the battery electrodes, current collector leads, or weldments, the possibility of shorting the battery exists if the interior insulation layer of the laminate fails. (The packaging laminate generally includes metal foil layers for structural integrity and hermeticity). Contact between the metal foil of the packaging and a conductive layer of the battery, shorts the battery thereby rendering it useless.
The present invention overcomes these and other problems and provides a battery wherein void spaces around the weldments and collector tabs within the battery package are reduced and the weldments are separated from the packaging laminate to reduce the likelihood of shorting as a result of the packaging laminate being drawn into electrical contact with a collector tab, weldment or lead.
In accordance with a preferred embodiment of the present invention, there is provided a Li-ion or Li-ion polymer battery, comprised of a battery assembly having a plurality of generally planar cathode sections, each having a flat, metallic cathode current collector tab extending therefrom, and one or more generally planar anode sections each having a flat, metallic anode current collector tab extending therefrom. The cathode sections and one or more anode sections are stacked together, wherein the cathode current collector tabs are aligned and the anode current collector tabs are aligned. A cathode tab weldment joins the cathode current collector tabs together and joins the tabs to a cathode battery lead. An anode tab weldment joins the anode current collector tabs together and joins the tabs to an anode battery lead. A battery package contains the battery assembly. The battery package has an interior space for receiving the anode tab weldment and the cathode tab weldment. The anode and cathode battery leads extend through the packaging to form external battery leads. A protective insert is disposed within the battery package. The insert surrounds the anode and cathode tab weldments and isolates the weldments from the battery package. The insert surrounds the battery leads where the battery leads extend through the package.
In accordance with another aspect of the present invention, there is provided a Li-ion or Li-ion polymer battery, comprised of a battery assembly having a plurality of generally planar cathode sections, each having a flat, metallic cathode current collector tab extending therefrom, and one or more generally planar anode sections each having a flat, metallic anode current collector tab extending therefrom. The cathode sections and one or more anode sections are stacked together. A cathode tab weldment joins the cathode current collector tabs together and to a cathode battery lead, an anode tab weldment joins the anode current collector tabs together and to an anode battery lead. A battery package having an interior space receives the battery assembly, the anode tab weldment and the cathode tab weldment with the anode and cathode battery leads extending through the packaging to form external battery leads. A molded insert disposed within the battery package surrounds the anode and cathode tab weldments and isolates the weldments from the battery package.
It is an object of the present invention to provide a Li-ion or Li-ion polymer battery that is less susceptible to failure from shorting during fabrication.
Another object of the present invention is to provide a Li-ion or Li-ion polymer battery as described above having a protective barrier around tab weldments within the battery.
A still further object of the present invention is to provide a Li-ion or Li-ion polymer battery having protective layers around the battery leads in the vicinity where the battery leads extend through the battery packaging.
A still further object of the present invention is to provide a Li-ion or Li-ion polymer battery as described above, wherein the protective barrier and the protective layers are part of an integrally formed insert.
These and other objects will become apparent from the following description of preferred embodiments of the invention, taken together with the accompanying drawings.